1. Field of the Invention
The present invention relates to an expansion valve and, more particularly to an expansion valve suitable for a refrigeration cycle.
2. Description of the Related Art
A refrigeration cycle in an automotive air conditioner is generally configured such that the refrigeration cycle includes a compressor, a condenser, an expansion valve, and an evaporator. The compressor compresses a circulating refrigerant. The condenser condenses the compressed refrigerant. The expansion valve throttles and expands the condensed liquid refrigerant and delivers it by turning it into a spray. Then the evaporator evaporates the misty refrigerant and thereby cools the air inside a vehicle's passenger compartment by the evaporative latent heat. Used as the expansion valve is a thermostatic expansion valve that senses the temperature and pressure of refrigerant at an outlet side of the evaporator such that, for example, the refrigerant led out from the evaporator has a predetermined degree of superheat and that controls the flow rate of refrigerant delivered to the evaporator by opening and closing a valve section.
Such an expansion valve includes a body formed with a first passage for passing the refrigerant flowing from the condenser to the evaporator and a second passage for passing the refrigerant returned from the evaporator and then supplying the refrigerant to the compressor. A valve hole is formed in the first passage, and a valve element is so provided as to face the valve hole. The valve element, which moves toward and away from the valve hole, regulates the flow rate of refrigerant flowing toward the evaporator. Also, provided at one end of the body is a power element that senses the temperature and pressure of refrigerant flowing through the second passage so as to be activated. The drive force of the power element is transmitted to the valve element by way of an elongated shaft. The shaft passes through an insertion hole formed in a partition wall, which divides between the first passage and the second passage, is slidably supported by the insertion hole. One end side of the shaft is connected to the power element, whereas the other end thereof is connected to the valve element by passing through the valve hole (see Reference (1) in the following Related Art List, for instance).